I keep my store-bought bread in the freezer and I've noticed that after it's frozen, every slice has a lot of small ice crystals on one side, but almost none on the other. I was wondering if it had to do with the opening of the bag or the direction it faces in the freezer so the last time I bought a loaf I put it with the sealed opening facing the back of the freezer, when normally I put it facing the front of the freezer. In both cases the crystals formed on the side facing the back of the freezer with almost none on the side facing the door. What causes the ice formation to be uneven?


I have experimented further and discovered that the ice crystals form after the bread is already frozen. The longer the bread is left in the freezer, the larger and more numerous the visible ice crystals get. Turning the bread around after a few days causes the ice crystals to form on the other side of each slice without noticeably reducing the ice that's already formed.

1 Answer 1


Your freezer causes this, as your experiment has shown.

Freezers don't magically cool down their contents, like ovens have a heat source, freezers have a "cold source", so in your case the back cools / freezes first, encouraging condensation and subsequently the formation of ice crystals on the colder parts. If your freezer has an auto-defrost cycle, this may contribute as well.

  • This doesn't explain why the sides facing the back, which are further from the source of "cold" form the crystals. You would think being closer to the back would make it colder.
    – CJ Dennis
    Commented May 4, 2016 at 9:26
  • @CJDennis I would expect the back being the coldest part in your freezer? So sides facing the back cool down faster. Humidity collects (condenses) there, causing a build-up of ice.
    – Stephie
    Commented May 4, 2016 at 9:28
  • What is interesting is that turning the bread around after a few days causes ice crystals to form on the other side of each slice. The bread is already frozen, so it's not cooling down anymore. The frozen water in the bread is obviously subliming, but I can't see a reason for it to only be deposited on one side of each slice, especially when having all the slices together insulates the bread from any minor temperature differences that might exist in the freezer.
    – CJ Dennis
    Commented Jun 5, 2016 at 1:47

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